1. Field of the Invention
The present invention relates to a surface-following type measuring machine, and more particularly to a surface-following type measuring machine which measures the surface roughness or contour of an object with a stylus thereof disposed in contact with the surface of the workpiece such that one of the stylus and the workpiece is moved relative to the other.
2. Prior Art
Surface roughness or contour measuring machines are known, which measure the surface roughness or contour of an object.
Measuring machines of this kind include a contact measuring machine having a contact-type stylus as shown in FIG. 1, which is equipped with a detector 5 comprised of a frame 10 which is moved relative to an object to be measured, by a moving mechanism, not shown, a measuring arm 11 supported via a shaft 12 by the frame 10 for swinging about the shaft 12 and carrying a stylus 15 at its tip, a balance weight 16 movably fitted on the measuring arm 11, for adjusting a measuring force acting upon the measuring arm 11, i.e. the force of contact of the stylus 15 with the object, such that the stylus 15 contacts the surface of an object to be measured with a predetermined measuring force, and a displacement detecting device 21 formed of a differential transformer or the like, for detecting an amount of displacement of the measuring arm 11 during swinging.
The measuring arm 11 is adapted to carry various types of styluses 15 and stylus holders 14 holding the stylus 15 such that the stylus 15 and the stylus holder 14 can be replaced with other ones, so as to be able to follow various surface contours of objects to be measured.
In measuring, a stylus 15 and a stylus holder 14 which are suitable for the surface contour of an object to be measured are selected and mounted on the measuring arm 11. The stylus 15 of the measuring arm 11 is brought into contact with the surface of the object, and then the measuring arm 11 is moved along the surface of the object by the moving mechanism. The measuring arm 11 swings according to the surface contour of the object, whereby the amount of displacement of the measuring arm 11 during swinging is detected by the displacement detecting device 21. The surface contour of the object or the like can be determined from the detected amount of displacement of the measuring arm 11 during swinging and the amount of movement of the same.
According to the conventional surface roughness or contour measuring machine, each time the stylus 15 and the stylus holder 14 are replaced with other ones, the balance weight 16 is adjusted, that is, the position of the balance weight 16 is moved in the longitudinal direction of the measuring arm 11, using a tension gauge or an electronic scale, such that the force of contact of the stylus 15 with the object to be measured, i.e. the measuring force, becomes equal to a predetermined value. This adjusting operation causes degraded operation efficiency and forms a great burden on the operator.